Golf club head that optimizes products of inertia

ABSTRACT

A golf club having products of inertia Ixy, Ixz and Iyz with absolute values below 100 g-cm 2  is disclosed herein. The golf club has a large volume, a high moment of inertia, or both. Preferably, the moment of inertia, Izz, of the golf club head about a vertical axis Z through the center of gravity ranges from 3000 g-cm 2  to 5000 g-cm 2 , and a moment of inertia, Iyy, about a horizontal axis Y through the center of gravity of the golf club head ranges from 1900 g-cm 2  to 2050 g-cm 2 . Preferably, the golf club head is composed of plies of pre-preg sheets. The volume of the golf club head preferably varies from 300 cm 3  to 600 cm 3 .

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part application ofco-pending U.S. patent application Ser. No. 09/796,951, filed on Feb.27, 2001, which is a continuation-in-part application of co-pending U.S.patent application Ser. No. 09/474,688, filed on Dec. 29, 1999, which isa continuation-in-part application of U.S. patent application Ser. No.08/958,723, filed on Oct. 23, 1997, and now U.S. Pat. No. 6,010,411, allof which are hereby incorporated by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a large volume golf club headthat optimizes the products of moments of inertia. More specifically,the present invention relates to a large volume golf club head that haslarge moments of inertia with small absolute values for the products ofinertia.

[0005] 2. Description of the Related Art

[0006] In recent years, substantial attention has been directed towardthe development of golf club heads having desired weight characteristicsand, in particular, toward the development of golf club heads having adesired center of gravity location. For example, a designer may want tolocate the center of gravity of a golf club head in a predetermined orpreferred position relative to the face or “sweet spot” of the golf clubhead to provide greater distance.

[0007] Because conventional golf club heads are typically made frommetal alloys or other materials having a substantially homogeneousdensity, the weight characteristics of such golf club heads aretypically defined by their overall shape. Thus, to alter the location ofthe center of gravity of a golf club head, it is often necessary toredesign the shape or configuration of the golf club head. However, thismay adversely impact other desired characteristics of the golf clubhead.

[0008] The design process may be further complicated where golf clubheads are manufactured using composite materials (typically carbonreinforced plastic). Because composite materials are typically lessdense than metal and other conventional materials, composite golf clubheads generally require additional weighting to achieve desired swingweights for finished golf clubs.

[0009] The Rules of Golf, established and interpreted by the UnitedStates Golf Association (“USGA”) and The Royal and Ancient Golf Club ofSaint Andrews, set forth certain requirements for a golf club head. Therequirements for a golf club head are found in Rule 4 and Appendix II. Acomplete description of the Rules of Golf are available on the USGA webpage at www.usga.org. Although the Rules of Golf do not expressly statespecific parameters for a golf club, Rule 4-1d states that the club headshall be generally plain in shape, and all parts shall be rigid,structural in nature and functional.

[0010] In the past few years, the volume of drivers and fairway woodshave increased to provide greater forgiveness for golfers. The BIGBERTHA® driver from Callaway Golf Company of Carlsbad, Calif., at 195cubic centimeters (cc) was the beginning of the large volume drivers.The BIG BERTHA® stainless steel driver was followed by the GREAT BIGBERTHA® titanium driver, also from the Callaway Golf Company, which hada volume of 250 cc. Then, the BIGGEST BIG BERTHA® titanium driver wasintroduced by the Callaway Golf Company, which had a volume of 295 cc.Recently, the forged titanium ERC® driver was introduced by the CallawayGolf Company, which had a volume of 300 cc. These large volume drivershave greater moments of inertia than previous golf clubs partly due totheir size, and the desire to locate the center of gravity in afavorable position. It was believed that increasing the moments ofinertia, Ixx, Izz and Iyy, of a driver would make the driver moreforgiving. However, forgiveness, in the form of reduced dispersion isnot a function of the moments of inertia, but rather a result of theproducts of inertia, Ixy, Ixz and Iyz.

[0011] The products of inertia relate moments about one axis with headrotations about another axis. These head rotations in turn causevertical or horizontal gear effect that impart increased or reducedbackspin and draw or fade spin to a golf ball. Unlike the spinsgenerated by conventional gear effect associated with Iyy and Izz, thesespins cannot be compensated for by adjusting the face bulge radius andthe face roll radius. As club heads become larger than 300 cc, andmoments of inertia become larger, Izz greater than 3000 grams centimetersquared and Iyy greater than 1800 grams, there is a propensity for theproducts of inertia to also become larger. As the products of inertiabecome larger, there is a deleterious effect on dispersion.

[0012] Thus, there is a need for a large volume golf club head withlarge moments of inertia, that have smaller products of inertia. Thisneed is difficult to meet since large products of inertia areby-products of large moments of inertia.

BRIEF SUMMARY OF THE INVENTION

[0013] The present invention provides a large volume golf club head withhigh moments of inertia that has smaller products of inertia. The golfclub head of the present invention provides all of the advantages oflarge volume golf club heads with large moments of inertia, such asgreater confidence and greater distance, without the attendant increasein dispersion. Thus, off-center hits have greater distance and increasedstraightness with the golf club head of the present invention, whichresults in more consistent golf ball flight and improved accuracy forthe golfer.

[0014] One aspect of the present invention is a golf club head includinga body having a crown, a sole and a striking plate. The body has ahollow interior. The golf club head has a volume ranging from 300 cubiccentimeters (“cm³”) to 600 cm³. Each of the products of inertia, Ixy,Ixz and Iyz, of the golf club head have an absolute value less than 100grams-centimeter squared (“g-cm²”).

[0015] Another aspect of the present invention is a high moment ofinertia golf club head having a body composed of a crown, a sole and astriking plate. The body has a hollow interior. The golf club head has amoment of inertia, Izz, about a vertical axis Z through the center ofgravity of the golf club head that ranges from 3000 g-cm² to 5000 g-cm². The golf club head also has a moment of inertia, Iyy, about thehorizontal axis Y through the center of gravity of the golf club headthat ranges from 1900 g-cm² to 2050 g-cm². Each of the products inertia,Ixy, Ixz and Iyz, of the golf club head have an absolute value less than100 g-cm².

[0016] Another aspect of the present invention is a golf club headhaving a body composed of a titanium alloy material and having a massless than 250 grams (“g”). A plurality of weight members having a massof less than 85 g are disposed within a hollow interior of the body. Thegolf club head has a moment of inertia, Izz, about a vertical axis Zthrough the center of gravity of the golf club head that ranges from3000 g-cm² to 5000 g-cm². The golf club head has a moment of inertia,Iyy, about the horizontal axis Y through the center of gravity of thegolf club head that ranges from 1900 g-cm² to 2050 g-cm². Each of theproducts inertia, Ixy, Ixz and Iyz, of the golf club head have anabsolute value less than 100 g-cm².

[0017] Another aspect of the present invention is a golf club headhaving a body composed of a steel alloy material and having a mass lessthan 250 grams (“g”). A plurality of weight members having a mass ofless than 85 g are disposed within a hollow interior of the body. Thegolf club head has a moment of inertia, Izz, about a vertical axis Zthrough the center of gravity of the golf club head that ranges from3000 g-cm² to 5000 g-cm². The golf club head has a moment of inertia,Iyy, about the horizontal axis Y through the center of gravity of thegolf club head that ranges from 1900 g-cm² to 2050 g-cm². Each of theproducts inertia, Ixy, Ixz and Iyz, of the golf club head have anabsolute value less than 100 g-cm².

[0018] Another aspect of the present invention is a golf club headhaving a crown, a sole, a striking plate and an external hosel extendingoutward from the crown. The golf club head has a moment of inertia, Izz,about a vertical axis Z through the center of gravity of the golf clubhead that ranges from 3000 g-cm² to 5000 g-cm². The golf club head has amoment of inertia, Iyy, about the horizontal axis Y through the centerof gravity of the golf club head that ranges from 1900 g-cm² to 2050g-cm². Each of the products inertia, Ixy, Ixz and Iyz, of the golf clubhead have an absolute value less than 100 g-cm².

[0019] Yet another aspect of the present invention is a golf club headhaving a crown, a sole and a striking plate. The golf club head has ahollow interior and is composed of a titanium alloy material. The golfclub head has a mass less than 250 g, and the striking plate hasconcentric regions of varying thickness. Weight members are disposedwithin the hollow interior of the body. The golf club head has a momentof inertia, Izz, about a vertical axis Z through the center of gravityof the golf club head that ranges from 3000 g-cm² to 5000 g-cm² . Thegolf club head has a moment of inertia, Iyy, about the horizontal axis Ythrough the center of gravity of the golf club head that ranges from1900 g-cm² to 2050 g-cm². Each of the products inertia, Ixy, Ixz andIyz, of the golf club head have an absolute value less than 100 g-cm².

[0020] Having briefly described the present invention, the above andfurther objects, features and advantages thereof will be recognized bythose skilled in the pertinent art from the following detaileddescription of the invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0021]FIG. 1 is a top plan view of a golf club head of the presentinvention.

[0022]FIG. 2 is a rear view of the golf club head of FIG. 1.

[0023]FIG. 3 is a toe end view of the golf club head of FIG. 1.

[0024]FIG. 4 is a heel end view of the golf club head of FIG. 1.

[0025]FIG. 5 is a cross-sectional view of the golf club head of FIG. 1along line 5-5.

[0026]FIG. 6 is a cross-sectional view of the golf club head of FIG. 1along line 6-6.

[0027]FIG. 7 is a cross-sectional view of the golf club head of FIG. 1along line 7-7.

[0028]FIG. 8 is a cross-sectional view of the golf club head of FIG. 1along line 8-8.

[0029]FIG. 8A is a cross-sectional view of the golf club head of analternative embodiment with a sole plate having a an attached hosel.

[0030]FIG. 9 is an exploded view of the golf club head of the presentinvention.

[0031]FIG. 9A is an exploded view of another alternative embodiment ofthe golf club head of the present invention.

[0032]FIG. 9B is an exploded view of yet another alternative embodimentof the golf club head of the present invention.

[0033]FIG. 9C is an exploded view of an alternative embodiment of thegolf club head of the present invention.

[0034]FIG. 10 is a top plan view of a golf club of the present inventionillustrating the Y axis and X axis.

[0035]FIG. 10A is a heel side plan view of a golf club of the presentinvention illustrating the Z axis and X axis.

[0036]FIG. 10B is a front plan view of a golf club of the presentinvention illustrating the Z axis and Y axis.

[0037]FIG. 11 is a front plan view of a golf club of the presentinvention illustrating the test frame coordinates X^(T) and Y^(T) andtransformed head frame coordinates Y^(H) and Z^(H).

[0038]FIG. 11A is a toe end view of the golf club of the presentinvention illustrating the test frame coordinate Z^(T) and transformedhead frame coordinates X^(H) and Z^(H).

[0039]FIG. 12 is an illustration of a center of gravity table for a golfclub head of the present invention used to measure the center of gravityalong the X axis.

[0040]FIG. 12A is an illustration of a center of gravity table for agolf club head of the present invention used to measure the center ofgravity along the Y axis.

[0041]FIG. 12B is an illustration of a center of gravity table for agolf club head of the present invention used to measure the center ofgravity along the Z axis.

[0042]FIG. 12C is an Inertia Dynamic Moment of Inertia Machine for agolf club head of the present invention and illustrates distance fromthe head to spin axis in the X^(T) direction.

[0043]FIG. 12D is an Inertia Dynamic Moment of Inertia Machine for agolf club head of the present invention and illustrates distance fromthe head to the spin axis in the Y^(T) direction.

[0044]FIG. 12E is an Inertia Dynamic Moment of Inertia Machine for agolf club head of the present invention and illustrates distance fromthe head to the spin axis in the Z^(T) direction.

[0045]FIG. 13 is an illustration of the effect of the product of inertiaIyz on a lofting force from a high-center strike of a golf ball againstthe striking plate a golf club.

[0046]FIG. 14 is an illustration of the effect of the product of inertiaIyz on a de-lofting force from a low-center strike of a golf ballagainst the striking plate a golf club.

[0047]FIG. 15 is an illustration of the effect of the product of inertiaIzy on a closing force from a off-center heel strike of a golf ballagainst the striking plate a golf club.

[0048]FIG. 16 is an illustration of the effect of the product of inertiaIzy on an opening force from a off-center toe strike of a golf ballagainst the striking plate a golf club.

[0049]FIG. 17 is a graph of dispersion (y-axis) vs. hit location(x-axis) for a golf club having a product of inertia Iyz=0, and a golfclub having a product of inertia Iyz=300.

[0050]FIG. 18 is a schematic drawing of a face of a golf club head withthe change in dispersion at three different hit locations per 100 g-cm²increase in the product of inertia Iyz.

[0051]FIG. 19 is a graph of dispersion (y-axis) vs. the product ofinertia Iyz (x-axis) for a pattern dispersion scatter.

[0052]FIG. 20 is a schematic drawing of a face of a golf club head withthe change in dispersion at nine different hit locations per 100 g-cm²increase in the product of inertia Iyz.

[0053]FIG. 21 is a graph of distance (y-axis) vs. the product of inertiaIyz (x-axis).

[0054]FIG. 22 is a schematic drawing of a face of a golf club head withthe change in distance at nine different hit locations per 100g-cm²increase in the product of inertia Iyz.

[0055]FIG. 23 is an illustration of the effect of the product of inertiaIxy on a vertical force from a off-center heel strike of a golf ballagainst the striking plate a golf club.

[0056]FIG. 24 is an illustration of the effect of the product of inertiaIxy on a vertical force from a off-center toe strike of a golf ballagainst the striking plate a golf club.

[0057]FIG. 25 is an illustration of the effect of the product of inertiaIxy on a lofting force from a high-center strike of a golf ball againstthe striking plate a golf club.

[0058]FIG. 26 is an illustration of the effect of the product of inertiaIxy on a de-lofting force from a low-center strike of a golf ballagainst the striking plate a golf club.

[0059]FIG. 27 is a graph of distance (y-axis) vs. the product of inertiaIxy (x-axis).

[0060]FIG. 28 is a schematic drawing of a face of a golf club head withthe change in distance at nine different hit locations per 100 g-cm²increase in the product of inertia Ixy.

[0061]FIG. 29 is a graph of dispersion (y-axis) vs. the product ofinertia Ixy (x-axis) for a pattern dispersion scatter.

[0062]FIG. 30 is a schematic drawing of a face of a golf club head withthe change in dispersion at nine different hit locations per 100 g-cm²increase in the product of inertia Ixy.

[0063]FIG. 31 is an illustration of the effect of the product of inertiaIxz on a vertical force from a off-center heel strike of a golf ballagainst the striking plate a golf club.

[0064]FIG. 32 is an illustration of the effect of the product of inertiaIxz on a vertical force from a off-center toe strike of a golf ballagainst the striking plate a golf club.

[0065]FIG. 33 is an illustration of the effect of the product of inertiaIxz on a closing force from a off-center heel strike of a golf ballagainst the striking plate a golf club.

[0066]FIG. 34 is an illustration of the effect of the product of inertiaIxz on an opening force from a off-center toe strike of a golf ballagainst the striking plate a golf club.

[0067]FIG. 35 is a graph of distance (y-axis) vs. the product of inertiaIxz (x-axis).

[0068]FIG. 36 is a schematic drawing of a face of a golf club head withthe change in distance at nine different hit locations per 100 g-cm²increase in the product of inertia Ixz.

[0069]FIG. 37 is a graph of dispersion (y-axis) vs. the product ofinertia Ixz (x-axis) for a pattern dispersion scatter.

[0070]FIG. 38 is a schematic drawing of a face of a golf club head withthe change in dispersion at nine different hit locations per 100 g-cm²increase in the product of inertia Ixz.

[0071]FIG. 39 is a top view of the golf club of the present inventionpartitioned into four quadrants by the X axis and the Y axis through thecenter of gravity.

[0072]FIG. 40 is a toe-side view of the golf club of the presentinvention partitioned into four quadrants by the X axis and the Z axisthrough the center of gravity.

[0073]FIG. 41 is a front view of the golf club of the present inventionpartitioned into four quadrants by the Y axis and the Z axis through thecenter of gravity.

[0074]FIG. 42 is a front view of the golf club of the present inventionpartitioned into four quadrants by the Y axis and the Z axis through thecenter of gravity, with a weight member positioned in quadrant I.

[0075]FIG. 43 is a front view of the golf club of the present inventionpartitioned into four quadrants by the Y axis and the Z axis through thecenter of gravity, with a weight member positioned in quadrant II.

DETAILED DESCRIPTION OF THE INVENTION

[0076] As shown in FIGS. 1-4, a golf club head of the present inventionis generally designated 20. All of the products of inertia (Ixy, Ixz andIyz) of the golf club head have an absolute value below 100 g-cm².Preferably, the products of inertia Ixy, Ixz and Iyz are less than 50g-cm², and most preferably the products of inertia Ixy, Ixz and Iyzapproach zero. The moment of inertia, Izz, about the Z axis for the golfclub head 20 of the present invention will range from 2800 g-cm² to 5000g-cm², preferably from 3000 g-cm² to 4500 g-cm², and most preferablyfrom 3500 g-cm² to 4000 g-cm². The moment of inertia, Iyy, about the Yaxis for the golf club head 20 of the present invention will range from1500 g-cm² to 2500 g-cm², preferably from 1800 g-cm² to 2100 g-cm², andmost preferably from 1900 g-cm² to 2050 g-cm². The golf club head 20will preferably have a volume ranging from 300 cubic centimeters (“cc”)to 600 cc, and more preferably from 325 cc to 525 cc.

[0077] The club head 20 is preferably a driver or fairway wood. In apreferred embodiment, the body 22 has a crown 24, a face 26, a sole 28and a ribbon 30 juxtaposed by the sole 28 and the crown 24. The ribbon30 generally extends from a toe end 32 to a heel end 34. The ribbon 30generally begins at one end of the face 26 and ends at an opposite endof the face 26. A rear 36 of the body 22 is opposite the face 26 and isdefined by portions of the ribbon 30, the crown 24 and the sole 28. Theribbon 30 increases the volume of the club head 20 and also assists increating a club head 20 with a higher moment of inertia as described ingreater detail below. Also, at the heel end 34 of the club head 20 is aninternal hosel 38 with a shaft opening 39 for insertion of a shafttherein.

[0078] The body 22 is composed of metals, composite materials, plasticmaterials and the like. In a preferred embodiment, the body 22 iscomposed of a plies of carbon pre-preg (pre-impregnated) sheets, or asimilar non-metallic material. In an alternative embodiment, the body 22is composed of a forged titanium alloy material. In another alternativeembodiment, the body is composed of a forged steel material. In yetanother alternative embodiment, the body 22 is composed of a casttitanium alloy material. Those skilled in the art will recognize thatthe body 22 may be composed of other materials without departing fromthe scope and spirit of the present invention.

[0079] The body 22 preferably has a hollow interior 44 defined by thewalls of the crown 24, face 26, sole 28 and ribbon 30. The walls of thecrown 24, sole 28 and ribbon 30 are relatively thin in order to minimizemass. The thickness of the wall of the face 26 is thicker than the otherwalls due to the necessity to sustain impact with a golf ball. If theface 26 is composed of a metal material, it preferably has variablethickness such as disclosed in U.S. Pat. No. 5,830,084 which is herebyincorporated by reference in its entirety.

[0080] As shown in FIGS. 5-7, the club head 20 has a plurality of weightmembers 40 disposed in the hollow interior 44 of the club head 20. Theweight members 40 are positioned for location of the center of gravity,to increase the moments of inertia and to minimize the products ofinertia. In a preferred embodiment, the weight members 40 are preferablyembedded within layers of the plies of pre-preg as described in greaterdetail below. In an alternative embodiment, such as a body composed of ametal material, each of the weight members 40 is a weight compartmentcomposed of the same material as the sole 29 for welding thereto. Theweight compartment defines a chamber of a predetermined volume with amaterial disposed therein having a density of seven to twentygrams/cubic centimeters and weighing between three to seventy grams(bismuth is one such material). Such a weighting member 40 is disclosedin co-pending U.S. patent application Ser. No. 09/633,010, filed on Aug.4, 2000, entitled Weighting System For Golf Club Head, which is herebyincorporated by reference in its entirety. In other embodiments, theweight member is a tungsten screw that is threadingly engaged into thebody 22 at the proper position, or a weight chip welded to the body 22.Those skilled within the pertinent art will recognize that other meansof weighting may be utilized without departing from the scope and spiritof the present invention.

[0081] As shown in FIG. 8, the sole plate 42 is attached to the exteriorsurface of the sole 28 and a hosel 38 is positioned within the hollowinterior 44 of the club head 20. The sole plate 42 is preferablycomposed of a metal such as aluminum, titanium or stainless steel. Thesole plate 42 weighs approximately 5 grams to 15 grams. The hosel 38 ispreferably composed of a metal such as stainless steel, or apolycarbonate material. The hosel 38 preferably weighs 12 to 16 grams.Another embodiment, shown in FIG. 8A, has an integral sole plate andhosel such as described in U.S. Pat. No. 6,244,976, filed on Dec. 29,1999, and entitled Integral Sole Plate And Hosel For A Golf Club Head,which is hereby incorporated by reference in its entirety. Those skilledin the pertinent art will recognize that the hosel may be an externalhosel that extends upward from the heel end of a golf club head, andthat such an external hosel would have an affect on the products ofinertia.

[0082] The weight members 40 are preferably composed of a film loadedwith a high density metal (like tungsten), or a metal material such ascopper, tungsten, steel, aluminum, tin, silver, gold, platinum, or thelike. A preferred weight member 40 is a thermoplastic material filledwith a metal to an appropriate density, and the metal filler may betungsten, brass, copper, steel, tin, or the like. Each weight member 40has a density greater than the material of the body 22. Each weightstrip 40 individually weighs approximately 3 grams to 35 grams, and morepreferably from 10 grams to 30 grams. In a preferred embodiment, thetotal combined weight of all of the weight members 40 is approximately30 grams to 80 grams, and most preferably 60 grams.

[0083] As shown in FIG. 9, preferably one weight member 40 is positionedin the upper ribbon 30 a in a U-like arrangement to increase the momentof inertia of the golf club head 20. A second balancing weight member40′ is positioned in the lower ribbon 30 b at the toe end 32 of the golfclub head 20 to balance the internal hosel 38 in order to reduce theproducts of inertia of the golf club head 20 below 100 g-cm². The weightmember 40 in the upper ribbon 30 a extends from approximately the heelend 34 of the face 26 through the rear 36 to the toe end 32 of the face26. However, this weight member 40 may only extend along the rear 36 ofthe upper ribbon 30 a, the heel end 34 of the upper ribbon 30 a, the toeend 32 of the upper ribbon 30 a, or any combination thereof. Thebalancing weight member 40′ in the lower ribbon section 30 b preferablymatches the moment of inertia effect of the internal hosel 38.

[0084] In a preferred embodiment with a body 22 composed of a compositematerial, the weight member 40 is a single piece co-cured to the upperribbon 30 a. However, two, three, four, or more weight members 40 maybeco-cured and extend along a portion of the upper ribbon 30 a. Themultiple weight members 40 may be partitioned horizontally orvertically. For example, as shown in FIG. 9A, three separate weightmembers 40 a-c are parallel to each other and extend along substantiallythe entire length of the upper ribbon 30 a. In an alternative embodimentas shown in FIG. 9B, multiple weight members 40 a-j are evenlydistributed along the entire length of the upper ribbon 30 a. In yetanother alternative embodiment shown in FIG. 9C, three separate weightmembers 40 a-c are positioned in the toe end 32 of the ribbon 30, therear 36 of the ribbon 30, and the heel end 32 of the ribbon 30. Thisembodiment does not have a balancing weight member 40′, however, theweight members 40 a-c vary in weight in order to have a golf club head20 with all products of inertia (Ixy, Ixz and Iyz) below 100 g-cm².Those skilled in the pertinent art will recognize that numerousvariations for the weight members 40 are possible without departing fromthe scope and spirit of the present invention.

[0085] As previously stated, the preferred composite material is pliesof carbon pre-preg sheets. Plies of pre-preg composite sheets aremanufactured by pulling strands of fiber in a parallel motion,preferably carbon or glass fiber, through a resin film and allowing theresin to partially cure or “stage”. When the resin is partially staged,the resin holds the fibers together such that the fibers form amalleable sheet with all of the fibers in a specific orientationrelative to an edge of the sheet. Exemplary carbon pre-preg fiber sheetsmay be obtained from Newport Composites of Santa Ana, Calif., Cytec Inc.of Anaheim, Calif., or Hexcel Inc. of Pleasonton, Calif. Alternatively,the layers 41 a-c of the composite body 22 may comprise a plurality ofplies of composite fiber without any resin, each typically comprising acontinuous fiber braid or mat, that are used to make a dry reinforcementpreform, as described in U.S. Pat. No. 6,010,411 filed on Oct. 23, 1997,which is hereby incorporated by reference in its entirety.

[0086] The composite body 22 may include one or more plies of pre-pregthat define structurally the various walls of the golf club head 20.Numerous other configurations may, of course, be utilized depending uponthe desired structural characteristics of the golf club head 20. Onesuch configuration is set forth in co-pending U.S. patent applicationSer. No. 09/474,670, filed on Dec. 29, 1999, entitled Composite GolfClub Head And Manufacturing Method, which is hereby incorporated byreference in its entirety.

[0087]FIGS. 10, 10A and 10B illustrate the axes of inertia through thecenter of gravity of the golf club head. The axes of inertia aredesignated X, Y and Z. The X axis extends from the striking plate 26through the center of gravity, CG, and to the rear of the golf club head20. The Y axis extends from the toe end 32 of the golf club head 20through the center of gravity, CG, and to the heel end 34 of the golfclub head 20. The Z axis extends from the crown 24 through the center ofgravity, CG, and to the sole 28.

[0088] As defined in Golf Club Design, Fitting, Alteration & Repair,4^(th) Edition, by Ralph Maltby, the center of gravity, or center ofmass, of the golf club head is a point inside of the club headdetermined by the vertical intersection of two or more points where theclub head balances when suspended. A more thorough explanation of thisdefinition of the center of gravity is provided in Golf Club Design,Fitting, Alteration & Repair.

[0089] The center of gravity and the moment of inertia of a golf clubhead 20 are preferably measured using a test frame (X^(T), Y^(T),Z^(T)), and then transformed to a head frame (X^(H), Y^(H), Z^(H)), asshown in FIGS. 11 and 11A. The center of gravity of a golf club head maybe obtained using a center of gravity table 55 having two weight scalesthereon, as shown in FIGS. 12, 12A and 12B. If a shaft is present, it isremoved and replaced with a hosel cube 57 that has a multitude of facesnormal to the axes of the golf club head 20. Given the weight of thegolf club head 20, the scales allow one to determine the weightdistribution of the golf club head when the golf club head is placed onboth scales simultaneously and weighed along a particular direction, theX, Y or Z direction. The weight scales are parallel to the earth'sgravity allowing the weight distribution along each direction to becalculated to determine the location of the center of gravity where:

W_(AO), W_(BO): Weight without head (fixture)

and

W^(AH), W_(BH): Weight with head

[0090] The X axis location is determined using the following equations:

ΣM _(A)=0=(W _(BH) −W _(BO))l−rW$r = \frac{\left( {W_{BH} - W_{BO}} \right)l}{W}$

 constraint:${\frac{l}{2} + d_{1}} = {r + X_{cg}^{T} + s + \frac{d}{2}}$

$X_{cg}^{T} = {\frac{\left( {W_{BH} - W_{BO}} \right)l}{W} + S + \frac{d}{2} - \frac{l}{2} - d_{1}}$

[0091] The Y axis location is determined using the following equations:

ΣM _(A)=0=(W _(BH) −W _(BO))l−rW$r = \frac{\left( {W_{BH} - W_{BO}} \right)l}{W}$

 Constraint: ${\frac{l}{2} + d_{1}} = {r + Y_{cg}^{T}}$

$Y_{cg}^{T} = {\frac{\left( {W_{BH} - W_{BO}} \right)l}{W} + \underset{\_}{l} + d_{2}^{1}}$

[0092] The Z axis location is determined using the following equations:

ΣM _(A) ={overscore (o)}=(W _(BH) −W _(BO))l−rW$r = \frac{\left( {W_{BH} - W_{BO}} \right)l}{W}$$\underset{\_}{{Constraint}\text{:}}$${\frac{l}{2} + d_{1}} = {r + Z_{cg}^{T}}$

$Z_{cg}^{T} = {\frac{\left( {W_{BH} - W_{BO}} \right)l}{W} - \frac{l}{2} - d_{1}}$

[0093] Once the test frame coordinates are determined, they aretransformed to head frame coordinates using the following equations:

X^(H) _(cg)=Z^(T) _(cg)

Y ^(H) _(cg) =X _(cg) cos (∝_(lie))+Y _(cg) sin (∝_(lie))−d _(z)/tan(∝_(lie))

Z ^(H) _(cg) =X _(cg) sin (∝_(lie))+Y _(cg) cos (∝_(lie))+d _(z)

[0094] or: $\begin{Bmatrix}X_{cg}^{H} \\Y_{cg}^{H} \\Z_{cg}^{H}\end{Bmatrix} = {{\begin{pmatrix}0 & 0 & 1 \\{\cos \left( \propto_{lie} \right)} & {\sin \left( \propto_{lie} \right)} & 0 \\{\sin \left( \propto_{lie} \right)} & {\cos \left( \propto_{lie} \right)} & 0\end{pmatrix}\quad \begin{Bmatrix}X_{cg}^{T} \\Y_{cg}^{T} \\Z_{cg}^{T}\end{Bmatrix}} + {z\begin{Bmatrix}0 \\{1/{\tan \left( \propto_{lie} \right)}} \\1\end{Bmatrix}}}$

[0095] The moment of inertia is measured using an Inertia Dynamic Momentof Inertia machine 59 as shown in FIGS. 12C, 12D and 12E. The machine 59has a rectangular plate with adapter holes spaced 0.5 inch apart fromeach other. The rectangular plate is mounted on the machine 59 to allowoscillation thereof. A golf club head 20 is placed on the rectangularplate and the time for one oscillation period is measured by themachine. The oscillation time is directly related to the moment ofinertia of the golf club head about the axis of rotation of the machine,which in effect is a single degree of freedom with the restoring forcegenerated by a torsional spring.

[0096] By changing the orientation of how the golf club head is mountedon the plate, the desired moment of inertia may be measured for an axis.Nine different orientations are required to generate an inertia tensor,and since the moment of inertia measured includes the plate and theadapter, nine additional measurements are required to measure thebaseline moment of inertia of the initial setup. The moment of inertiaof the golf club head is the difference between the measurement takenwith the golf club head, adapter and plate and the internal rotatingmass of the machine, and that of the just the adapter and plate and theinternal rotating mass of the machine. For the nine measurements donewith the golf club head, the orientations are the same from head tohead, the position on the rectangular plate depends on the center ofgravity of the particular golf club head. The nine measurements withoutthe golf club head are the same for orientation and the location of theadapter. The machine has a center of gravity and moment of inertiaprogram to calculate the adapter holes on the rectangular plate thatplace the center of gravity closest to the axis of rotation, therebyminimizing error. The program uses the parallel axis theorem to accountfor the axis of rotation not containing the center of gravity of thegolf club head. This will yield an inertia tensor about the center ofgravity, which in turn allows the moment of inertia about any axis to becalculated for the golf club head. TABLE ONE

[0097] Table One lists the location of the center of gravity, themoments of inertia about the center of gravity, and the products ofinertia for prior art composite golf club heads. The moment of inertiaIzz about the Z axis is less than 2436.00 g-cm² for any of the prior artcomposite heads. The highest moment of inertia, Izz, about the Z axis is2435.72 g-cm² for the Yonex 1 AERONA 300 composite driver. The moment ofinertia, Iyy, about the Y axis is less than 1300.00 g-cm² for any of theprior art composite heads. The highest moment of inertia, Iyy, about theY axis is 1298.21 g-cm² for the Daiwa 1, G 3 composite driver. The massfor all of the composite heads of Table One ranges from 186 grams to208.5 grams. Each of the composite golf clubs of Table One that have ahigh moment of inertia or a volume greater than 300 cc, have at leastone absolute value for the products of inertia that is over 100 g-cm².For example, the Yonex 1 AERONA 300 has the highest moment of inertia ofTable One, but its product of inertia Ixy is 205.06 g-cm². All of theabsolute values of the products of inertia of Daiwa 1, G-3 are below 100g-cm², but the G-3 has a golf club head volume of only 195 cc, and itshighest moment of inertia is only 1951.54 g-cm². Thus, the Daiwa 1, G-3fails to demonstrate a golf club with a high volume or high moment ofinertia and products of inertia below 100 g-cm². TABLE TWO Club HeadMass Ixx Iyy Izz Ixy Ixz lyz Volume GBB ® 189 1802 1752 2750 212 8 99250 9Deg BBB 9 Deg 189 2135 1763 2900 208 31 149 295 Hawk Eye ® 194 18861562 2607 134 −77 120 275 10 Deg Steelhead ™ 197 1722 1389 2300 238 −23143 225 Plus 10 Deg ERC ® 188 2119 1654 2697 155 −43 120 300

[0098] Table Two lists the moments of inertia about the center ofgravity, and the products of inertia for prior art metal golf club headsfrom Callaway Golf Company of Carlsbad, California, beginning with theGREAT BIG BERTHA® cast titanium driver in row 1, the BIGGEST BIG BERTHA®cast titanium driver in row 2, the GREAT BIG BERTHA® HAWK EYE® casttitanium driver in row 3, the BIG BERTHA® STEELHEAD PLUS™ cast stainlesssteel driver in row 4, and the ERC® forged titanium driver in row 5. Themoment of inertia Izz about the Z axis is less than 2900.00 g-cm² forany of the golf club heads of Table Two. The highest moment of inertia,Izz, about the Z axis, is 2900 g-cm² for the CALLAWAY GOLF® BIGGEST BIGBERTHA® driver. The moment of inertia, Iyy, about the Y axis is lessthan 1800.00 g-cm² for any of the club heads of Table Two. The mass forall of the club heads of Table Two ranges from 186 grams to 208.5 grams.All of the club heads of Table Two have at least one absolute value forthe products of inertia that is over 100 g-cm². For example, theproducts of inertia Iyz and Ixz for the GREAT BIG BERTHA® driver areunder an absolute value of 100 g-cm², but the product of inertia Ixy isover an absolute value of 100 g-cm². TABLE THREE Head Weighting Ixx IyyIzz Ixy Ixz Iyz Ex. 1 195 g 2700 2000 3500 75 75 75

[0099] Table Three lists the moment of inertia and products of inertiafor a golf club head 20 of the present invention. An “unweighted” clubhead 20 (without the weight members 40) weighs from 90 grams to 120grams thereby allowing for 60 grams to 105 grams of weight to be placedaccordingly to achieve the reduced products of inertia for the golf clubhead 20 of the present invention. The moment of inertia, Izz, about theZ axis for the golf club head 20 of the present invention will rangefrom 2800 g-cm² to 5000 g-cm², preferably from 3000 g-cm² to 4500 g-cm²,and most preferably from 3500 g-cm² to 4000 g-cm². The moment ofinertia, Iyy, about the Y axis for the golf club head 20 of the presentinvention will range from 1500 g-cm² to 2500 g-cm², preferably from 1800g-cm² to 2100 g-cm², and most preferably from 1900 g-cm² to 2050 g-cm².The product of inertia Ixy of the golf club head 20 of the presentinvention 20 has an absolute value less than 100 g-cm². Preferably, theproduct of inertia Ixy is less than 50 g-cm², and most preferably theproduct of inertia Ixy approaches zero. The product of inertia Ixz ofthe golf club head 20 of the present invention 20 has an absolute valueless than 100 g-cm². Preferably, the product of inertia Ixz is less than50 g-cm², and most preferably the product of inertia Ixz approacheszero. The product of inertia Iyz of the golf club head 20 of the presentinvention 20 has an absolute value less than 100 g-cm². Preferably, theproduct of inertia Iyz is less than 50 g-cm², and most preferably theproduct of inertia Iyz approaches zero.

[0100] FIGS. 13-38 illustrate how the products of inertia effect thedistance and dispersion of a golf ball struck with a golf club.

[0101]FIG. 13 illustrates the effects of the product of inertia, Iyz,for a lofting force from a high center hit. High center hits are definedas hits that have their impulse vector above the center of gravity ofthe golf club head 20, and low center hits are defined as hits that havetheir impulse vector below the center of gravity of the golf club head20. For a high center hits, as shown in FIG. 13, the product of inertiaIyz causes a lofting moment in the golf club head 20 which creates aclosing rotation thereby leading to a slice spin in the golf ball 63.

[0102]FIG. 14 illustrates the effects of the product of inertia, Iyz,for a de-lofting force from a low center hit. The product of inertia Iyzcauses a de-lofting moment in the golf club head 20 which creates anopening rotation thereby leading to a draw spin in the golf ball 63.

[0103]FIG. 15 illustrates the effects of the product of inertia, Iyz,for a closing force from an off center heel hit. The product of inertiaIyz causes a closing moment in the golf club head 20 which creates alofting rotation thereby leading to a top spin in the golf ball 63.

[0104]FIG. 16 illustrates the effects of the product of inertia, Iyz,for a opening force from an off center toe hit. The product of inertiaIyz causes an opening moment in the golf club head 20 which creates ade-lofting rotation thereby leading to a back spin in the golf ball 63.

[0105]FIG. 17 illustrates the effects of the product of inertia Iyz onthe dispersion of a golf ball. A golf club having a product of inertiaIyz of zero has a relatively small dispersion for any hit locationwhereas golf club having a product of inertia Iyz of 300 (absolutevalue) has a dispersion that varies 35 feet depending on the hitlocation.

[0106]FIG. 18 illustrates the effect on dispersion from increasing theproduct of inertia Iyz. A high center hit will have a 6.9 feetdispersion to the right (R) per 100 g-cm² increase in Iyz, and a lowcenter hit will have a 4.2 feet dispersion to the left (L) per 100 g-cm²increase in Iyz.

[0107]FIG. 19 illustrates the effect on dispersion from increasing theproduct of inertia Iyz for the average of a nine hit pattern. FIG. 20illustrates the nine-hit location effect on dispersion from increasingthe product of inertia Iyz.

[0108]FIGS. 21 and 22 illustrate the effect on distance from increasingthe product of inertia Iyz for the average of a nine hit pattern. Forexample, a high center hit will have a −0.3 yard effect on distance per100 g-cm² increase in Iyz, and a high toe hit will have a 1.5 yardeffect on distance per 100 g-cm² increase in Iyz.

[0109]FIG. 23 illustrates the effects of the product of inertia Ixy fora vertical force from an off-center heel hit. The product of inertia Ixycauses a toe-up moment in the golf club head 20 which creates a loftingrotation thereby leading to a top spin in the golf ball 63.

[0110]FIG. 24 illustrates the effects of the product of inertia Ixy fora vertical force from an off-center toe hit. The product of inertia Ixycauses a toe-down moment in the golf club head 20 which creates ade-lofting rotation thereby leading to a back spin in the golf ball 63.

[0111]FIG. 25 illustrates the effects of the product of inertia Ixy fora lofting force from a high center hit. The product of inertia Ixycauses a lofting moment in the golf club head 20 which creates a toe-uprotation thereby leading to the golf ball 63 having a back spin for aheel hit, a top spin for a toe hit and a fade spin for a center hit.

[0112]FIG. 26 illustrates the effects of the product of inertia Ixy fora de-lofting force from a low center hit. The product of inertia Ixycauses a de-lofting moment in the golf club head 20 which creates atoe-down rotation thereby leading to the golf ball 63 having a back spinfor a toe hit, a top spin for a heel hit and a fade spin for a centerhit.

[0113]FIGS. 27 and 28 illustrate the effect on distance from increasingthe product of inertia Ixy for the average of a nine hit pattern. Forexample, a high center hit will have a −0.3 yard effect on distance per100 g-cm² increase in Ixy, and a low toe hit will have a −0.9 yardeffect on distance per 100 g-cm² increase in Ixy.

[0114]FIGS. 29 and 30 illustrate the effect on dispersion fromincreasing the product of inertia Ixy for the average of a nine hitpattern. For example, a high center hit will have a 3.9 feet effect tothe right per 100 g-cm² increase in Ixy, and a high toe hit will have a2.1 feet effect to the right per 100 g-cm² increase in Ixy.

[0115]FIG. 31 illustrates the effects of the product of inertia Izx fora vertical force from an off-center heel hit. The product of inertia Izxcauses a toe-up moment in the golf club head 20 which creates a closingrotation thereby leading to a slice spin in the golf ball 63.

[0116]FIG. 32 illustrates the effects of the product of inertia Izx fora vertical force from an off-center toe hit. The product of inertia Izxcauses a toe-down moment in the golf club head 20 which creates anopening rotation thereby leading to a draw spin in the golf ball 63.

[0117]FIG. 33 illustrates the effects of the product of inertia, Izx,for a closing force from an off center heel hit. The product of inertiaIzx causes a closing moment in the golf club head 20 which creates atoe-up rotation thereby leading to a back spin in the golf ball 63.

[0118]FIG. 34 illustrates the effects of the product of inertia, Izx,for a opening force from an off center toe hit. The product of inertiaIzx causes an opening moment in the golf club head 20 which creates atoe-down rotation thereby leading to a back spin in the golf ball 63.

[0119]FIGS. 35 and 36 illustrate the effect on distance from increasingthe product of inertia Ixz for the average of a nine hit pattern. Forexample, a high heel hit will have a −0.9 yard effect on distance per100 g-cm² increase in Ixz, and a low toe hit will have a −0.9 yardeffect on distance per 100 g-cm² increase in Ixz.

[0120]FIGS. 37 and 38 illustrate the effect on dispersion fromincreasing the product of inertia Ixz for the average of a nine hitpattern. For example, a high heel hit will have a 4.5 feet effect to theright per 100 g-cm² increase in Ixz, and a high toe hit will have a 3.9feet effect to the left per 100 g-cm² increase in Ixz.

[0121] As shown in FIG. 39, the club head 20 of the present invention ispartitioned into four regions, I, II, III and IV. Mass added in eitherregions I or III increases the product of inertia Ixy whereas mass addin either regions II or IV decreases the product of inertia Ixy. Thelocation at which mass is added within any given region determines themagnitude of change to Ixy. An incremental change in Ixy is determinedby the amount of mass “m” added and the X and Y coordinate location ofthe mass (wherein X and Y are measured from the center of gravity, CG,of the golf club head 20) using the following formula:

Ixy=§§mdxdy

[0122] As a result, adding mass along the X or Y axis has no affect onIxy while adding mass along a diagonal line bisecting the X and Y axesresults in maximal affect (additive or subtractive) on Ixy.

[0123] As shown in FIG. 40, the club head 20 of the present invention ispartitioned into four regions, I, II, III and IV. Mass added in eitherregions I or III increases the product of inertia Ixz whereas mass addin either regions II or IV decreases the product of inertia Ixz. Thelocation at which mass is added within any given region determines themagnitude of change to Ixz. An incremental change in Ixz is determinedby the amount of mass “m” added and the X and Z coordinate location ofthe mass (wherein X and Z are measured from the center of gravity, CG,of the golf club head 20) using the following formula:

Ixz=§§mdxdz

[0124] As a result, adding mass along the X or Z axis has no affect onIxz while adding mass along a diagonal line bisecting the X and Z axesresults in maximal affect (additive or subtractive) on Ixz.

[0125] As shown in FIG. 41, the club head 20 of the present invention ispartitioned into four regions, I, II, III and IV. Mass added in eitherregions I or III increase the product of inertia Iyz whereas mass add ineither regions II or IV decreases the product of inertia Iyz. Thelocation at which mass is added within any given region determines themagnitude of change to Iyz. An incremental change in Iyz is determinedby the amount of mass “m” added and the Y and Z coordinate location ofthe mass (wherein Y and Z are measured from the center of gravity, CG,of the golf club head 20) using the following formula:

Iyz=§§mdydz

[0126] As a result, adding mass along the Y or Z axis has no affect onIyz while adding mass along a diagonal line bisecting the Y and Z axesresults in maximal affect (additive or subtractive) on Iyz.

[0127] To illustrate the affect on Iyz, a five gram weight member 40′ isadded to the club head 20 as shown in FIG. 42. The weight is added at alocation in quadrant I at four centimeters along the Y axis from thecenter of gravity and one centimeter along Z axis from the center ofgravity. Using the above formula, Iyz=§§mdydz, then Iyz=5 g*4 cm*1 cm=20g-cm². The precise affect of the weight member 40′ on Iyz is determinedby accounting for the finite size of the mass by integrating over thearea of the weight member 40′.

[0128] A second example is shown in FIG. 43 wherein the five gram weightmember 40′ is positioned at a location in quadrant II at threecentimeters along the Y axis from the center of gravity and onecentimeter along the Z axis below the center of gravity. Using the aboveformula, Iyz=§§mdydz, then Iyz=5 g*3 cm*-1 cm=−15 g-cm². As statedabove, the precise affect of the weight member 40′ on Iyz is determinedby accounting for the finite size of the mass by integrating over thearea of the weight member 40′.

[0129] From the foregoing it is believed that those skilled in thepertinent art will recognize the meritorious advancement of thisinvention and will readily understand that while the present inventionhas been described in association with a preferred embodiment thereof,and other embodiments illustrated in the accompanying drawings, numerouschanges, modifications and substitutions of equivalents may be madetherein without departing from the spirit and scope of this inventionwhich is intended to be unlimited by the foregoing except as may appearin the following appended claims. Therefore, the embodiments of theinvention in which an exclusive property or privilege is claimed aredefined in the following appended claims.

We claim as our invention:
 1. A golf club head comprising: a body havinga crown, a sole and a striking plate, the body having a hollow interior;wherein the golf club head has a volume ranging from 300 cm³ to 600 cm³,and each of the products inertia, Ixy, Ixz and Iyz, of the golf clubhead have an absolute value less than 100 g-cm².
 2. The golf club headaccording to claim 1 wherein the a moment of inertia, Izz, is greaterthan 3000 g-cm² about a vertical axis Z through the center of gravity ofthe golf club head.
 3. The golf club head according to claim 1 whereinthe body is composed of a plurality of layers of plies of pre-pregmaterial.
 4. The golf club head according to claim 1 wherein each of theproducts inertia, Ixy, Ixz and Iyz, of the golf club head have anabsolute value less than 50 g-cm².
 5. The golf club head according toclaim 1 wherein the body is composed of a material selected from thegroup consisting of titanium, titanium alloy, steel, stainless steel,and amorphous metals.
 6. The golf club head according to claim 3 whereinfurther comprising a weight strip that is composed of a materialselected from the group consisting of a densified loaded film, copper,tungsten and bismuth.
 7. The golf club head according to claim 1 whereinthe moment of inertia, Izz, about the vertical axis Z through the centerof gravity of the golf club head ranges from 3500 g-cm² to 5000 g-cm².8. The golf club head according to claim 1 wherein the golf club headhas a moment of inertia, Iyy, of at least 1900 g-cm² about a horizontalaxis Y through the center of gravity of the golf club head.
 9. The golfclub head according to claim 1 where in the golf club head has a volumethat ranges from 350 cm³ to 525 cm³.
 10. The golf club head according toclaim 1 wherein the golf club head weighs between 150 grams to 250grams.
 11. The golf club head according to claim 1 wherein the moment ofinertia, Iyy, about the horizontal axis Y through the center of gravityof the golf club head ranges from 1900 g-cm² to 2050 g-cm².
 12. The golfclub head according to claim 1 wherein the moment of inertia, Izz, aboutthe vertical axis Z through the center of gravity of the golf club headranges from 3700 g-cm² to 5000 g-cm².
 13. A golf club head comprising: abody having a hollow interior and composed of a composite material, thebody having a face, a sole, a crown, a ribbon juxtaposed by the sole andthe crown, a heel end and a toe end; and a plurality of weight strips,each of the plurality of weight strips composed of a material having adensity greater than the composite material, each of the plurality ofweight strips disposed on the ribbon; wherein the golf club head has avolume ranging from 300 cm³ to 600 cm³, and each of the productsinertia, Ixy, Ixz and Iyz, of the golf club head have an absolute valueless than 100 g-cm².
 14. A golf club head comprising: a body having acrown, a sole and a striking plate, the body having a hollow interior;wherein the golf club head has a moment of inertia, Izz, about avertical axis Z through the center of gravity of the golf club head thatranges from 3000 g-cm² to 5000 g-cm², a moment of inertia, Iyy, aboutthe horizontal axis Y through the center of gravity of the golf clubhead that ranges from 1900 g-cm² to 2050 g-cm², and each of the productsinertia, Ixy, Ixz and Iyz, of the golf club head have an absolute valueless than 100 g-cm².
 15. A golf club head comprising: a body having acrown, a sole and a striking plate, the body having a hollow interior,the body composed of a titanium alloy material, the body having a massless than 250 g; a plurality of weight members disposed within thehollow interior of the body, the plurality of weight members having atotal mass of less than 85 g; wherein the golf club head has a moment ofinertia, Izz, about a vertical axis Z through the center of gravity ofthe golf club head that ranges from 3000 g-cm² to 5000 g-cm², a momentof inertia, Iyy, about the horizontal axis Y through the center ofgravity of the golf club head that ranges from 1900 g-cm² to 2050 g-cm²,and each of the products inertia, Ixy, Ixz and Iyz, of the golf clubhead have an absolute value less than 100 g-cm².
 16. A golf club headcomprising: a body having a crown, a sole and a striking plate, the bodyhaving a hollow interior, the body composed of a steel alloy material; aplurality of weight members disposed within the hollow interior of thebody, the plurality of weight members having a total mass of less than85 g; wherein the golf club head has a moment of inertia, Izz, about avertical axis Z through the center of gravity of the golf club head thatranges from 3000 g-cm² to 5000 g-cm², a moment of inertia, Iyy, aboutthe horizontal axis Y through the center of gravity of the golf clubhead that ranges from 1900 g-cm² to 2050 g-cm², and each of the productsinertia, Ixy, Ixz and Iyz, of the golf club head have an absolute valueless than 100 g-cm².
 17. A golf club comprising: a golf club head havinga crown, a sole, a striking plate and an external hosel extendingoutward from the crown, the golf club head having a hollow interior;wherein the golf club head has a moment of inertia, Izz, about avertical axis Z through the center of gravity of the golf club head thatranges from 3000 g-cm² to 5000 g-cm², a moment of inertia, Iyy, aboutthe horizontal axis Y through the center of gravity of the golf clubhead that ranges from 1900 g-cm² to 2050 g-cm², and each of the productsinertia, Ixy, Ixz and Iyz, of the golf club head have an absolute valueless than 100 g-cm².
 18. A golf club comprising: a golf club head havinga crown, a sole and a striking plate, the golf club head having a hollowinterior, the golf club head composed of a titanium alloy material, thegolf club head having a mass less than 250 g, the striking plate havingconcentric regions of varying thickness; a plurality of weight membersdisposed within the hollow interior of the body, the plurality of weightmembers having a total mass of less than 85 g; wherein the golf clubhead has a moment of inertia, Izz, about a vertical axis Z through thecenter of gravity of the golf club head that ranges from 3000 g-cm² to5000 g-cm², a moment of inertia, Iyy, about the horizontal axis Ythrough the center of gravity of the golf club head that ranges from1900 g-cm² to 2050 g-cm 2, and each of the products inertia, Ixy, Ixzand Iyz, of the golf club head have an absolute value less than 100g-cm².
 19. A golf club head comprising: a body having a crown, a soleand a striking plate, the body having a hollow interior; wherein thegolf club head has a volume ranging from 300 cm³ to 600 cm³, the productof inertia, Ixy, of the golf club head has an absolute value less than50 g-cm², the product of inertia, Ixz, of the golf club head has anabsolute value less than 100 g-cm², and the product of inertia, Iyz, ofthe golf club head has an absolute value less than 100 g-cm².
 20. A golfclub head comprising: a body having a crown, a sole with a ribbon, and astriking plate, the body having a hollow interior; a plurality of weightmembers disposed within the hollow interior of the body, the pluralityof weight members having a total mass of less than 85 g; wherein thegolf club head has a volume ranging from 300 cm³ to 600 cm³, a moment ofinertia, Izz, about a vertical axis Z through the center of gravity ofthe golf club head that ranges from 3000 g-cm² to 5000 g-cm², theproduct of inertia, Ixy, of the golf club head has an absolute valueless than 50 g-cm², the product of inertia, Ixz, of the golf club headhas an absolute value less than 100 g-cm², and the product of inertia,Iyz, of the golf club head has an absolute value less than 100 g-cm².